Suspended or dropped ceilings are widely used in residential, commercial and industrial buildings. Ceiling panels which define this dropped ceiling are generally suspended by a grid-like support structure. This support structure is secured to the building frame and/or the existing ceiling of the room. The space between the dropped ceiling and the actual ceiling is used for enclosing electrical and communication cables, fire protection, conduits, and ventilation ducts.
A dropped ceiling is usually installed after temporary walls are erected to partition off work space. These walls do not extend from the floor to the actual ceiling, but instead, only go as high as the dropped ceiling. Therefore, oftentimes an open and unobstructed area remains above the dropped ceiling.
Panels used in dropped ceiling may be designed to serve a variety of functions. First, the panels may be designed to serve as an attractive means for concealing the ducts, wiring, plumbing, etc. located above the panels. The panels are attractive when viewed from below, because a decorative lamina is applied to the underside of the panel. This lamina may have a smooth or a textured surface which is pleasing to the eye.
Second, the panels are often designed to contain a material which allows the panel to serve as a fire barrier. Should a fire start in an enclosed room, the panels help contain the fire to that room by preventing the fire from entering the open area above the dropped ceiling. Thus, the fire is prevented from spreading over the wall of one room into another.
Next, panels have been designed to help create a quiet working atmosphere by absorbing undesired sound or noise produced in the room below. A panel's ability to absorb noise can be measured by its Noise Reduction (NR) coefficient. The larger this coefficient is for a given panel, the more noise the panel absorbs. For example, a panel with an NR coefficient of 0.99 sabins will absorb almost all the noise which comes in contact with the panel's surface.
Finally, panels have been designed to prevent noise from traveling from one room to another. This problem occurs when noise, which is not absorbed by the ceiling panel, passes through the panel and into the open space above the dropped ceiling. This noise may then travel into an adjacent room.
To overcome this problem, ceiling panels may be installed that inhibit transmission of noise through the panel. Thus, the noise generated in one room is prevented from entering the space above the dropped ceiling. A panel's characteristic to inhibit the transmission of noise is commonly measured by its Sound Transmission (ST) coefficient. The greater the ST coefficient of a given panel, the less sound or noise the panel will transmit.
Today, there is a need to produce a ceiling panel which possesses all four of the above characteristics. One situation which has given rise to this need is the current design of commercial and industrial work space. These work spaces are frequently designed to place open work areas next to enclosed rooms. As open work areas generally produce a great deal of noise, ceiling panels with a large NR coefficient are needed to keep the areas as quiet as possible. Yet, it is also necessary to have ceiling panels with a large ST coefficient in open work areas. This prevents noise from jumping over the walls and into enclosed rooms which are intended to be as quiet as possible.
A solution to the above problem is to combine several layers of materials for the purpose of achieving all desired ceiling panel characteristic. Still, the more layers which are required to produce the desired ceiling panel, the greater will be the labor, material and manufacturing costs. Furthermore, these ceiling panels must be as space efficient as possible because shipping costs for these panels are often based on the bulk volume of the space taken up in transit. Thus, the problem becomes how to make an inexpensive, space efficient, fire resistant ceiling panel which provides both high NR and ST coefficients.
An additional problem faced by the ceiling panel industry is the untimely destruction of panels due to water leaks or humidity which cause the panels to warp around their edges. Once warped, the panels become unsightly and require the additional expense of early replacement.
The present invention is provided to solve these and other problems.